CAS No 89-86-1 , 2,4-dihydroxybenzoic acid

Title: b-Resorcylic Acid
CAS Registry Number: 89-86-1
CAS Name: 2,4-Dihydroxybenzoic acid
Synonyms: 2,4-dihydroxybenzenecarboxylic acid; BRA
Molecular Formula: C7H6O4
Molecular Weight: 154.12
Percent Composition: C 54.55%, H 3.92%, O 41.52%
Literature References: Prepared from resorcinol and KHCO3 in glycerol or water by heating and passing CO2 through the mixture: Brunner, Ann. 351, 320 (1907). Cf. Bistrycki, Kostanecki, Ber. 18, 1984 (1885); Nierenstein, Clibbens, Org. Synth. coll. vol. II, 557 (1943).
Properties: Hydrated crystals from water. Becomes anhydr at 100°, mp 213° (rapid heating). pK (25°) 3.30. Sol in hot water, alcohol, ether, olive oil. Boiling with water, acids or salt solns results in loss of CO2.
Melting point: mp 213° (rapid heating)
pKa: pK (25°) 3.30
Use: Intermediate for dyestuffs and drugs; spot test reagent for iron.